Wideband aircraft antenna with extended frequency range

Abstract

A compact, broadband, aerodynamically streamlined, mechanically rugged antenna for aircraft and other applications has been developed that has a VSWR of 2:1 or better, and has uniform patterns with no nulls over a wide 8:1 bandwidth from 225 MHz to 1.85 GHz. The antenna has an aerodynamically streamlined shape, with a rugged housing capable of withstanding velocities up to Mach 2. In addition to its usage on aircraft, this antenna would be useful in a wide range of applications as a general purpose, wide bandwidth omnidirectional antenna. The antenna achieves its performance capabilities with the use of a double Vivaldi element feed section, an upper extension made of resistive film or R-card, and a shaped boundary between the feed and upper sections of the radiating elements.

What is claimed is: 
     
       1. A broadband, low voltage standing wave ratio, omnidirectional, antenna, comprising:
 a ground plane having a feed point; 
 a first antenna section; 
 a second antenna section; 
 said first and second antenna sections extend upward from the feed point in a parabolic fashion of equal radius, each section forming a Vivaldi structure in the respective portion of the antenna section proximately located to the ground plane and subsequently embodying simple curved sections such that each antenna element has an opposed, joined surface above the ground plane feed point and generally perpendicular thereto. 
 
     
     
       2. The antenna of  claim 1 , wherein the simple curved section is approximately 30 degrees. 
     
     
       3. The antenna of  claim 1 , wherein each antenna section has a height less than three inches from the feedpoint to the top of the antenna. 
     
     
       4. The antenna of  claim 1 , wherein the width of the antenna is approximately four and one-half inches. 
     
     
       5. The antenna of  claim 1 , further comprising a blade-shaped protective housing about the antenna. 
     
     
       6. The antenna of  claim 5 , wherein the housing is made of FR-4 material. 
     
     
       7. The antenna of  claim 1 , wherein a frequency range of the antenna is between 225 MHz and 1.85 GHz. 
     
     
       8. The antenna of  claim 5 , further comprising a filler material between the antenna and the housing. 
     
     
       9. A method for efficiently radiating/receiving electromagnetic radiation in an omnidirectional pattern, with a low voltage standing wave ratio, comprising:
 forming an antenna having a double Vivaldi element, each Vivaldi element having a bottom portion having edges with Vivaldi curves, and a top portion extending above each Vivaldi curve and further incorporating a curved shaped edge; 
 joining a non-metallic, co-planar upper element resistive sheet from each curve shaped edge to the portion proximately above each Vivaldi curve; 
 coupling a feed to a feed-side of the Vivaldi element; and 
 at least one of exciting the feed with a radio signal or receiving a radio signal from the feed. 
 
     
     
       10. The method of  claim 9 , wherein the curve shaped edge is approximately 30 degrees. 
     
     
       11. The method of  claim 9 , wherein a top edge of the resistive sheet is curved. 
     
     
       12. The method of  claim 9 , wherein a resistance of the resistive sheet is approximately 150 ohms/square. 
     
     
       13. A broadband, low voltage standing wave ratio, omnidirectional, planar antenna, comprising:
 a ground plane having a feed point; 
 a first antenna section; 
 a second antenna section; 
 said first and second antenna sections extend upward from the feed point in a parabolic fashion of equal radius, each section forming a Vivaldi structure in the respective portion of the antenna section proximately located to the ground plane and subsequently embodying mirror coplanar vertical extensions with simple curved sections such that each antenna element has an opposed, joined surface above the ground plane feed point and generally perpendicular thereto. 
 
     
     
       14. The antenna of  claim 13 , further comprising a blade-shaped protective housing about the antenna. 
     
     
       15. The antenna of  claim 14 , wherein the housing is made of FR-4 material. 
     
     
       16. The antenna of  claim 13 , wherein a resistance of the resistive sheet is approximately 150 ohms/square. 
     
     
       17. The antenna of  claim 14 , further comprising a filler material between the antenna and the housing. 
     
     
       18. The antenna of  claim 13 , wherein said antenna has a height of less than ten inches, a broadside width of less than six inches and an edge thickness of less than one inch.